When operating electrical consumers in the electrical onboard network of an aircraft, there may be subharmonic/interharmonic and harmonic frequencies of the current or voltage. Depending on the frequency range of the subharmonic/interharmonic and harmonic frequencies, there may be resonance oscillations in the supply voltage and mechanical oscillations within the generator drive. Oscillations of this type are undesirable.
In one example, electrical consumers having an electric motor and an inverter connected thereto, according to the selected architecture, may cause subharmonic/interharmonic and harmonic frequencies or oscillations of varying strength of the current depending on the operating state of the motor (rotational speed, network frequency and type of electric motor).
One approach for reducing subharmonic and interharmonic oscillations is reducing the oscillations occurring from the inverter by means of complex inverter switching processes. These include operating the electric machine by means of complex, sensor-free processes by means of sinusoidal rotary fields. This requires considerable complexity in terms of control for producing and controlling said rotary fields and further leads to higher switching losses of the inverter and to a significantly increased development complexity.
Examples of electrical consumers of this type include fans for ventilation, such as those described in DE 10 2008 025 960 A1 and US 2011/0111683 A1.
In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.